1. Field of the Invention
The present invention relates to a motor and a washing machine with the same mounted therein, and more particularly to a motor including a stator having air flow channels formed at the upper and lower parts thereof, whereby the stator is effectively cooled, and a washing machine with the same mounted therein.
2. Description of the Related Art
As shown in FIGS. 1 and 2, the conventional motor comprises: a stator 10; a rotor 20 rotatably disposed around the stator 10 while the rotor 20 is spaced apart from the stator 10 by a prescribed distance of air gap G; and a rotor cup 30, to which the rotor 20 is fixed at the inner circumference thereof in such a manner that the rotor cup 30 is rotated along with the rotor 20.
The stator 10 comprises: a ring-shaped core 12; a plurality of teeth 16 evenly attached to the outer circumference of the ring-shaped core 12 in the circumferential direction while a prescribed slot 14 is formed between one of the teeth 16 and the neighboring tooth; and coils 18 wound on the teeth 16, respectively, the coils 18 being connected to an external source of electricity.
The rotor 20 is made of a ring-shaped magnet with north poles and south poles alternately arranged. When electric current is supplied to the coils, the rotor 20 interacts electromagnetically with the stator 10 so that the rotor 20 is rotated.
At the inner bottom surface of the rotor cup 30 are formed a plurality of rectangular cooling-holes 32, which are drilled in the radial direction. At one side of each of the cooling-holes 32 is provided a rectangular blade 34. When the rotor cup 30 is rotated along with the rotor 20, external cool air is introduced into the rotor cup 30 through the cooling-holes 32 by means of a blowing force from the blades 34. The cool air introduced into the rotor cup 30 passes through the air gap G and the slots 14, and is then discharged to the outside through the opened upper part of the rotor cup 30 so that the stator 10 and the rotor 20 are cooled.
In the case that the above-mentioned motor is mounted in a washing machine having a housing 54 fixed to the bottom part of an outer tub 52 mounted in a case 50, as shown in FIG. 3, the stator 10 is provided at the inner circumference thereof with a boss 10b. The boss 10b has a second fixing-hole 10a, which vertically communicates with a first fixing-hole 54a formed at the bottom part of the housing 54. Bolts 56 are inserted through the first fixing-holes 54a and the second fixing-holes 10a, and are then securely engaged in nuts 57 at the ends of the bolts 56 as shown in FIG. 3, so that the stator 10 is securely fixed to the housing 54 of the washing machine.
Through the center of the bottom part of the rotor cup 30 is fixedly inserted the lower end of a rotating shaft 58. The upper end of the rotating shaft 58 is inserted through the housing 54 and the outer tub 52 of the washing machine in such a manner that the rotating shaft 58 is rotatably mounted in the outer tub 52. The upper end of the rotating shaft 58 is fixed to an inner tub 60 of the washing machine where the laundry is put in such a manner that the rotating shaft 58 is rotated along with the inner tub 60 of the washing machine. Consequently, the rotor cup 30 is rotated along with the inner tub 60 of the washing machine by means of the rotating shaft 58.
When an electromagnetic force is generated between the stator 10 and the rotor 20 as electric current is supplied to the coils 18, the rotor 20, the rotor cap 30, the rotating shaft 58, and the inner tub 60 are simultaneously rotated.
At this time, the remaining upper part of the rotor cup 30, excluding the slots 14 and the air gap G, is blocked by means of the housing 54 of the washing machine and the stator 10. As a result, air is discharged to the outside of the motor only through the slots 14 and the air gap G so that the motor is cooled.
In the above-mentioned conventional art, however, the stator 10 is placed adjacent to the rotor 20 since the electromagnetic force becomes larger as the stator 10 gets near to the rotor 20. For example, the air gap G is set to below 0.7 mm in order that the rotor 20 can be rotated, and the slots 14 are very small in order to increase the rotation efficiency of the motor. As a result, external air introduced through the cooling-holes 34 cannot smoothly flow to the upper part of the rotor cup 30 through the air gap G and the slots 14. Consequently, the motor cannot be sufficiently cooled, whereby heat loss of the motor is high, and the motor is easily deteriorated.